/**
 * Copyright (c) 2011-2014 Felix Gnass
 * Licensed under the MIT license
 */
(function(root, factory) {

        // CommonJS
        if (typeof exports == 'object') {
            module.exports = factory();
        }
        // AMD module
        else if (typeof define == 'function' && define.amd) {
            define(factory);
        }
        // Browser global
        else {
            root.Spinner = factory();
        }

    }
    (this, function() {
        "use strict";

        var prefixes = ['webkit', 'Moz', 'ms', 'O'] /* Vendor prefixes */ ,
            animations = {} /* Animation rules keyed by their name */ ,
            useCssAnimations /* Whether to use CSS animations or setTimeout */

        /**
         * Utility function to create elements. If no tag name is given,
         * a DIV is created. Optionally properties can be passed.
         */
        function createEl(tag, prop) {
            var el = document.createElement(tag || 'div'),
                n

            for (n in prop) el[n] = prop[n]
            return el
        }

        /**
         * Appends children and returns the parent.
         */
        function ins(parent /* child1, child2, ...*/ ) {
            for (var i = 1, n = arguments.length; i < n; i++)
                parent.appendChild(arguments[i])

            return parent
        }

        /**
         * Insert a new stylesheet to hold the @keyframe or VML rules.
         */
        var sheet = (function() {
            var el = createEl('style', {
                type: 'text/css'
            })
            ins(document.getElementsByTagName('head')[0], el)
            return el.sheet || el.styleSheet
        }())

        /**
         * Creates an opacity keyframe animation rule and returns its name.
         * Since most mobile Webkits have timing issues with animation-delay,
         * we create separate rules for each line/segment.
         */
        function addAnimation(alpha, trail, i, lines) {
            var name = ['opacity', trail, ~~(alpha * 100), i, lines].join('-'),
                start = 0.01 + i / lines * 100,
                z = Math.max(1 - (1 - alpha) / trail * (100 - start), alpha),
                prefix = useCssAnimations.substring(0, useCssAnimations.indexOf('Animation')).toLowerCase(),
                pre = prefix && '-' + prefix + '-' || ''

            if (!animations[name]) {
                sheet.insertRule(
                    '@' + pre + 'keyframes ' + name + '{' +
                    '0%{opacity:' + z + '}' +
                    start + '%{opacity:' + alpha + '}' +
                    (start + 0.01) + '%{opacity:1}' +
                    (start + trail) % 100 + '%{opacity:' + alpha + '}' +
                    '100%{opacity:' + z + '}' +
                    '}', sheet.cssRules.length)

                animations[name] = 1
            }

            return name
        }

        /**
         * Tries various vendor prefixes and returns the first supported property.
         */
        function vendor(el, prop) {
            var s = el.style,
                pp, i

            prop = prop.charAt(0).toUpperCase() + prop.slice(1)
            for (i = 0; i < prefixes.length; i++) {
                pp = prefixes[i] + prop
                if (s[pp] !== undefined) return pp
            }
            if (s[prop] !== undefined) return prop
        }

        /**
         * Sets multiple style properties at once.
         */
        function css(el, prop) {
            for (var n in prop)
                el.style[vendor(el, n) || n] = prop[n]

            return el
        }

        /**
         * Fills in default values.
         */
        function merge(obj) {
            for (var i = 1; i < arguments.length; i++) {
                var def = arguments[i]
                for (var n in def)
                    if (obj[n] === undefined) obj[n] = def[n]
            }
            return obj
        }

        /**
         * Returns the absolute page-offset of the given element.
         */
        function pos(el) {
            var o = {
                x: el.offsetLeft,
                y: el.offsetTop
            }
            while ((el = el.offsetParent))
                o.x += el.offsetLeft, o.y += el.offsetTop

            return o
        }

        /**
         * Returns the line color from the given string or array.
         */
        function getColor(color, idx) {
            return typeof color == 'string' ? color : color[idx % color.length]
        }

        // Built-in defaults

        var defaults = {
            lines: 12, // The number of lines to draw
            length: 7, // The length of each line
            width: 5, // The line thickness
            radius: 10, // The radius of the inner circle
            rotate: 0, // Rotation offset
            corners: 1, // Roundness (0..1)
            color: '#000', // #rgb or #rrggbb
            direction: 1, // 1: clockwise, -1: counterclockwise
            speed: 1, // Rounds per second
            trail: 100, // Afterglow percentage
            opacity: 1 / 4, // Opacity of the lines
            fps: 20, // Frames per second when using setTimeout()
            zIndex: 2e9, // Use a high z-index by default
            className: 'spinner', // CSS class to assign to the element
            top: '50%', // center vertically
            left: '50%', // center horizontally
            position: 'absolute' // element position
        }

        /** The constructor */
        function Spinner(o) {
            this.opts = merge(o || {}, Spinner.defaults, defaults)
        }

        // Global defaults that override the built-ins:
        Spinner.defaults = {}

        merge(Spinner.prototype, {

            /**
             * Adds the spinner to the given target element. If this instance is already
             * spinning, it is automatically removed from its previous target b calling
             * stop() internally.
             */
            spin: function(target) {
                this.stop()

                var self = this,
                    o = self.opts,
                    el = self.el = css(createEl(0, {
                        className: o.className
                    }), {
                        position: o.position,
                        width: 0,
                        zIndex: o.zIndex
                    }),
                    mid = o.radius + o.length + o.width

                css(el, {
                    left: o.left,
                    top: o.top
                })

                if (target) {
                    target.insertBefore(el, target.firstChild || null)
                }

                el.setAttribute('role', 'progressbar')
                self.lines(el, self.opts)

                if (!useCssAnimations) {
                    // No CSS animation support, use setTimeout() instead
                    var i = 0,
                        start = (o.lines - 1) * (1 - o.direction) / 2,
                        alpha, fps = o.fps,
                        f = fps / o.speed,
                        ostep = (1 - o.opacity) / (f * o.trail / 100),
                        astep = f / o.lines

                    ;
                    (function anim() {
                        i++;
                        for (var j = 0; j < o.lines; j++) {
                            alpha = Math.max(1 - (i + (o.lines - j) * astep) % f * ostep, o.opacity)

                            self.opacity(el, j * o.direction + start, alpha, o)
                        }
                        self.timeout = self.el && setTimeout(anim, ~~(1000 / fps))
                    })()
                }
                return self
            },

            /**
             * Stops and removes the Spinner.
             */
            stop: function() {
                var el = this.el
                if (el) {
                    clearTimeout(this.timeout)
                    if (el.parentNode) el.parentNode.removeChild(el)
                    this.el = undefined
                }
                return this
            },

            /**
             * Internal method that draws the individual lines. Will be overwritten
             * in VML fallback mode below.
             */
            lines: function(el, o) {
                var i = 0,
                    start = (o.lines - 1) * (1 - o.direction) / 2,
                    seg

                function fill(color, shadow) {
                    return css(createEl(), {
                        position: 'absolute',
                        width: (o.length + o.width) + 'px',
                        height: o.width + 'px',
                        background: color,
                        boxShadow: shadow,
                        transformOrigin: 'left',
                        transform: 'rotate(' + ~~(360 / o.lines * i + o.rotate) + 'deg) translate(' + o.radius + 'px' + ',0)',
                        borderRadius: (o.corners * o.width >> 1) + 'px'
                    })
                }

                for (; i < o.lines; i++) {
                    seg = css(createEl(), {
                        position: 'absolute',
                        top: 1 + ~(o.width / 2) + 'px',
                        transform: o.hwaccel ? 'translate3d(0,0,0)' : '',
                        opacity: o.opacity,
                        animation: useCssAnimations && addAnimation(o.opacity, o.trail, start + i * o.direction, o.lines) + ' ' + 1 / o.speed + 's linear infinite'
                    })

                    if (o.shadow) ins(seg, css(fill('#000', '0 0 4px ' + '#000'), {
                        top: 2 + 'px'
                    }))
                    ins(el, ins(seg, fill(getColor(o.color, i), '0 0 1px rgba(0,0,0,.1)')))
                }
                return el
            },

            /**
             * Internal method that adjusts the opacity of a single line.
             * Will be overwritten in VML fallback mode below.
             */
            opacity: function(el, i, val) {
                if (i < el.childNodes.length) el.childNodes[i].style.opacity = val
            }

        })


        function initVML() {

            /* Utility function to create a VML tag */
            function vml(tag, attr) {
                return createEl('<' + tag + ' xmlns="urn:schemas-microsoft.com:vml" class="spin-vml">', attr)
            }

            // No CSS transforms but VML support, add a CSS rule for VML elements:
            sheet.addRule('.spin-vml', 'behavior:url(#default#VML)')

            Spinner.prototype.lines = function(el, o) {
                var r = o.length + o.width,
                    s = 2 * r

                function grp() {
                    return css(
                        vml('group', {
                            coordsize: s + ' ' + s,
                            coordorigin: -r + ' ' + -r
                        }), {
                            width: s,
                            height: s
                        }
                    )
                }

                var margin = -(o.width + o.length) * 2 + 'px',
                    g = css(grp(), {
                        position: 'absolute',
                        top: margin,
                        left: margin
                    }),
                    i

                function seg(i, dx, filter) {
                    ins(g,
                        ins(css(grp(), {
                                rotation: 360 / o.lines * i + 'deg',
                                left: ~~dx
                            }),
                            ins(css(vml('roundrect', {
                                    arcsize: o.corners
                                }), {
                                    width: r,
                                    height: o.width,
                                    left: o.radius,
                                    top: -o.width >> 1,
                                    filter: filter
                                }),
                                vml('fill', {
                                    color: getColor(o.color, i),
                                    opacity: o.opacity
                                }),
                                vml('stroke', {
                                    opacity: 0
                                }) // transparent stroke to fix color bleeding upon opacity change
                            )
                        )
                    )
                }

                if (o.shadow)
                    for (i = 1; i <= o.lines; i++)
                        seg(i, -2, 'progid:DXImageTransform.Microsoft.Blur(pixelradius=2,makeshadow=1,shadowopacity=.3)')

                for (i = 1; i <= o.lines; i++) seg(i)
                return ins(el, g)
            }

            Spinner.prototype.opacity = function(el, i, val, o) {
                var c = el.firstChild
                o = o.shadow && o.lines || 0
                if (c && i + o < c.childNodes.length) {
                    c = c.childNodes[i + o];
                    c = c && c.firstChild;
                    c = c && c.firstChild
                    if (c) c.opacity = val
                }
            }
        }

        var probe = css(createEl('group'), {
            behavior: 'url(#default#VML)'
        })

        if (!vendor(probe, 'transform') && probe.adj) initVML()
        else useCssAnimations = vendor(probe, 'animation')

        return Spinner

    }));